Centrifugal pump



Feb. 10, 1942. I w. H. LANNERf 2,272,469

dENTRIFueAL PUMP Filed Dec. 25, 1939 INVENTOR.

ATTORNEY.

Patented Feb. 10, 194;

UNITED. "STATES amass tion of- Illinois Application December 23, 1939.Serial No. 310, 73

2 Claims. (Cl. 103-103) a from a suitable source of power such as an'elec- This inventionrelates to centrifugal pumps of that type which areemployed for pumping sewage and other' liquids containing solids such aspaper, rags, stringy substances, trash and other semi-solids.Considerable difficulty has been encountered in centrifugal pumps ofthis typebecause of the likelihood of the rags, paperand other stringymaterial lodging on. or clinging to the heel of the impeller blade insuch quantities as to interfere with the operation of the pump andsometimes clogging the same to such an ex-v tent that it must shut down..Many attempts have been made to overcome this difllculty with more orless success, and the principal object of this invention is to eliminatethe possibility of solids being caught blades.

I have accomplished this result by employing an entirely differentprinciple of operation than has been employed heretofore in centrifugalpumps. In accordance with the present invention the interior of the Pu pis so shaped that the velocity of the liquid is increased as it passesthrough the eye of the impeller, then decreased in an inlet chamber,-and its velocity again increased as it passes the Heel of an impellerblade.

The result of this change of velocity of the 'liquid causes the solidsto bunch together as the velocityis slowed up in the inlet chamber, and

the increase of velocityimmediately thereafter eausesthe solids to bedrawn across the space in front of the heel of an impeller blade,thereby preventing the solids from being caught on the 7 heel. Theinvention consists, therefore, in the several novel features ofconstruction, arrangement and combination of parts hereinafter fully.set forth and claimed.

The invention is clearly illustrated. in the drawing accompanying thisspecification, in which: I

Fig. 1 is a central vertical longitudinal section through to centrifugalpump, embodying a simple form of h broken away. I

Fig. 2 is a vertical cross section of theimpeller taken on the line 2-2of Fig. 1.

r Fig. 3 is a vertical crosssectionof the impeller taken on the line 3-3of Fig. l, and

Fig. 4'is a detailed horizontal cross section taken-on the line of Figs.1 and}.

Referring to said drawing, the reference character I designates the,base of a" centrifugal pump, upon which is mounted a housing 8containing bearings, one of'which is seen-at T, in

on the heels of impeller l mounted on its tapered end as by a hub is;de-

e present invention, with certain parts i.

tric motor (not shown). Bolted to the housing v is one side wall 9 ofthe pump casing, which side wall may be formed with a housing il' con-'5 ,tainingpacking ll around the impeller shaft.

Bolted to the side wall a is the end wall I! of the 'pump casing, whichcontains the usual volute chamber of the pump. If desired,- the otherside wall I; of the pump casing may be cast integral with the endwallit. The inlet pipe to the pump 'is shown at M. and as shown it hasabolting 1 flange l5, rigid on its end, whichis bolted to the side wallit of the pump casing, as by bolts and nuts I. The discharge 'endof thevolute chamber is shown at IT. Obviously the construction of the partsabove described may be varied to suit the type of. pumpio which theinvention is applied. 1

, Theimpellershaft projects into the interior of the pump .casing,- andthe impeller i8 is sirably a bolt 2!, threaded in the end of the shaftfastens the impeller thereon. The impeller shown is of the'closed type;it"has two spaced 25 disposed in co-axial alisnment with the inlet pipe.and eye. Thefaceof the suction inlet conposegof the reduction indiameter of the eyeas compared with that of the inlet pipe is toincrease the velocity of the liquid passing through theeye orthe-impeller.

The eye opens to an inlet chamber 26 in'the .impellenjin which chamberthe velocity of the liquid lei-decreased as it passes throughdt, and,this slowing up of the .velocity allows the solids The heel 21 of eachimpellerblade is made relatively narrow and is convex or rounded off asseen in Figures 2 and 3, and merges into the inner and outer faces 28,29 of the blades. Instead of being parallel-with the axis of theimpeller,

the heel of each-blade preferably slopes at. an angle to the axis of theimpeller, and the inner and outer faces of the blades, beginning at thewhich is mounted an impeller shaft 8,. driven 5 heel, slope from oneside wall to theother for a PATENT pan I side wall ll of the casinghas asuction inlet 25 to bunch together before proceeding through thepassages between the impeller bladest short distance and gradually mergeinto the nels formed by the side walls and blades may be.

circular or other rounded contour,.a.s is desired. The inner face 28 ofeachbiade extends in a curvilinear line from the convex face of theheel, running from the curved face of the eye along a line which isnon-concentric with respect to the axis of the impeller, and approachesthe opposite heel to a point'approxlmately opposite the crown of saidheel, whereby the cross sectional area of the passages between the heelsand the leadin ends of the blades decreases to a point approximatelyoppositethe crown of said heel, and then continues along a curvilinearline approximately concentric with the convex face of the heel of theother blade, and then takes a curvature suitable for most efficientpumping of the liquid, the extremity of the inner face ending at theperiphery of the impeller.

The outer face 29 of each blade extends from the convex face of the heelalong a curved line substantially paralleling the curvature of the innerface of the tail end of the companion blade and then curves in adirection around but excentric to the axis of the impeller, andprogresses towards the periphery of the impeller along a curved linebest adapted for efficiently impelling the liquid. Desirably the tailend of each blade extends for some distance beyond the heel of thecompanion blade.

As is well upderstood, the concave inner faces of the impeller bladesimpart suction upon the liquid and the convex sides thereof serve to,impel the liquid from the inlet chamber of the impeller to the volutechamber of the casing. However, by reason of the shape of the forward orentering ends of the sides of the blades, the velocity of the liquidisincreased as it passes the heel of a companion blade, and the suctioneffect of the inner face of each blade adjacent it heel, serves to drawthe liquids and solids away from the opposite heel, thereby preventingthe solids from being caught thereon.

' I claim as new and desire to secure by Letters Patent:

1. A centrifugal pump casing. having a suction inlet and an impellerrotating in the casing,-said *impeller being formed with an eye and withimpeller blades, means to increase the velocity of liquids passingthrough the eye of the impeller and means to decrease the velocity ofthe liquid after passing through the eye, each of said impeller bladeshaving a leading end adjacent the eye and a trailing end at theperiphery of the impeller, a convex heel at its leading end and innerand outer faces that progress from the convex heel to the periphery oncurvilinear lines. the inner and outer curved faces of eachblade'diverging from the convex heel to provide a thickened part beyondthe heel and then convergin toward the trailing end, with the inner faceof each blade substantially paralleling the convex heel and outer faceof the thickened portion of the other blade to formpassages between theblades whereby the velocity. of the liquid passing through thepassageway is increased across the path of travel of the heel.

2. A centrifugal pump comprising a pump casing having a suction inletwhich converges toward the interior of the pump casing, an impellerrotating in said pump casing and having an eye of substantially the samediameter as the smallest diameter of the suction inlet whereby thevelocity of liquids passing through the eye is increased. said impellerhaving an enlarged inlet chamber into which the eye opens, said impelleralso having impeller blades, each of said impeller blades having aleading end adjacent the eye and a trailing end at the periphery oftheimpeller, a convex heel at its leading end and inner and outer facesthat progress from the convex heel to the periphery on curvilinearlines, the inner and outer curved faces of each blade diverging from theconvex heel to provide a thickened part beyond the heel and thenconverging toward the trailing end, with the inner face ofeach bladesubstantially paralleling the convex heel and outer face of thethickened portion of the other blade to form passages between the bladeswhereby the velocity of the liquid passing through the passageway isincreased across the path of travel of the heel.

WILLIAM H. LANNERT.

